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Journal of Thermal Analysis and Calorimetry

, Volume 81, Issue 2, pp 425–433 | Cite as

Thermal behavior of short-range-order in quenched Cu-12 at% Mn assessed by DSC

  • E. Donoso
  • G. Díaz
  • A. Varschavsky
Article

Summary

The ordering behavior of quenched Cu-12 at% Mn was investigated by differential scanning calorimetry (DSC) under increasing temperature conditions. The ordering process can be better explained in terms of a homogeneous short-range-order (SRO) rather than a disperse-short-range-order (DSRO) model as for concentrated Cu-γMn solid solutions. At the employed high quench rates ordering is established in one stage here termed stage 1, assisted by excess vacancies. This stage obeys a first order kinetics law, being the effective activation energy consistent with a weighed average sum of the activation energy for migration of free and bound vacancies. An estimated solute-vacancy binding energy of 15 kJ mol-1 seems quite reasonable for this alloy together with the assessed activation energy for complex migration of 92.6 kJ mol-1. By adopting a first SRO order parameter based in quasi-chemical theory in pair approximation and using boundary values calculated from displayed features of DSC traces, the retained degree of quenched-in order at room temperature was calculated. This procedure also enabled to estimate an ordering energy of -2.7 kJ mol-1. The effect of quenching temperature demonstrate that for smaller vacancy sink densities, the retained degree of order at room temperature goes through a minimum.

kinetics DSC vacancies bound vacancies Cu-12 at% Mn quenched short-range-order 

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Copyright information

© Springer-Verlag/Akadémiai Kiadó 2005

Authors and Affiliations

  • E. Donoso
    • 1
  • G. Díaz
    • 2
  • A. Varschavsky
    • 3
  1. 1.Universidad de Chile, Facultad de Ciencias Físicas y Matemáticas, Instituto de Investigaciones y Ensayes de Materiales
  2. 2.Universidad de Chile, Facultad de Ciencias Físicas y Matemáticas, Instituto de Investigaciones y Ensayes de Materiales
  3. 3.Universidad de Chile, Facultad de Ciencias Físicas y Matemáticas, Instituto de Investigaciones y Ensayes de Materiales

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